From: Jason Gunthorpe <jgg@ziepe.ca>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>,
Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] iommu: Use mutex instead of spinlock for iommu_device_list
Date: Mon, 29 Jan 2024 10:57:31 -0400 [thread overview]
Message-ID: <20240129145731.GD50608@ziepe.ca> (raw)
In-Reply-To: <BN9PR11MB5276E9618612DCF4DAE0CAE68C7E2@BN9PR11MB5276.namprd11.prod.outlook.com>
On Mon, Jan 29, 2024 at 08:04:35AM +0000, Tian, Kevin wrote:
> > From: Lu Baolu <baolu.lu@linux.intel.com>
> > Sent: Friday, January 26, 2024 6:54 PM
> >
> > The iommu_device_lock spinlock was used to protect the iommu device
> > list. However, there is no requirement to access the iommu device
> > list in interrupt context. Therefore, a mutex is sufficient.
>
> I don't think that interrupt is the reason for spinlock otherwise
> spin_lock_irqsave() should be used instead.
Right, there is no touch of this from an interrupt
I suspect it is following the the general kernel wisdom that a
spinlock is better if the critical sections are very small.
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Jason
next prev parent reply other threads:[~2024-01-29 14:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-26 10:53 [PATCH v2 0/2] Use right iommu_ops for mock device Lu Baolu
2024-01-26 10:53 ` [PATCH v2 1/2] iommu: Use mutex instead of spinlock for iommu_device_list Lu Baolu
2024-01-29 8:04 ` Tian, Kevin
2024-01-29 14:57 ` Jason Gunthorpe [this message]
2024-01-26 10:53 ` [PATCH v2 2/2] iommu: Probe right iommu_ops for device Lu Baolu
2024-01-29 8:07 ` Tian, Kevin
2024-01-29 14:58 ` Robin Murphy
2024-01-29 15:37 ` Jason Gunthorpe
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